Non-uniform, protective coating on a flexible substrate

ABSTRACT

In the present invention, a protective coating is preferably formed as a plurality of dots upon a surface to be protected. The dots have a selected size, cover a selected amount of the underlying surface, and are preferably isolated from one another by uncoated surfaces. This coating not only provides the coated substrate or object (and the cured coating itself) with significantly increased flexibility and formability, but also with a wide range of possible surface finishes and textures. Due to the increased coating flexibility and formability, the coated substrate or object can be partially or even fully cured prior to forming operations such as injection molding or film shaping. The substrate or object is therefore less susceptible to damage from handling and from machine operations. One highly preferred coating embodiment is produced with ink having a controllable stipple amount for a significantly increased range of possible coating finishes and textures.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application is a divisional of U.S. patentapplication Ser. No. 09/828,308, filed on Apr. 6, 2001, entitled METHODOF FORMING A NON-UNIFORM, PROTECTIVE COATING ON A FLEXIBLE SUBSTRATE,the entire contents of which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to coatings, and more particularlyto protective coatings and methods of forming such coatings.

BACKGROUND OF THE INVENTION

[0003] A large number of coatings exist for protecting surfaces on awide variety of industrial and commercial products, many of whichpresent challenges to a satisfactory coated end product. A problem thatis common to many applications arises as a result of the flexure ordeformation of a coated surface. A protective coating on a surface thatis flexible or is subjected to deformation is generally more likely tofail, whether by losing adherence, peeling, cracking, or otherwiseexposing some or all of the underlying surface, by wrinkling orbuckling, by developing coating areas that are stressed or weakened, andthe like. A number of these problems can occur in the relatively newtechnology of in-mold decoration (IMD). Generally speaking, IMD is theapplication of text, a pattern, or graphics to a molded part as part ofthe molding process.

[0004] A popular type of IMD process employs the use of insert moldingin which a formable film is layered with a protective coating on oneside (referred to as the “first” side or surface), and is printed withtext, a pattern, or graphics on an opposite side (referred to as the“second” side or surface). With reference to FIG. 1, which illustrates aconventional IMD process in flowchart form, the film is first printed or“decorated” with the text, pattern, or graphics in a conventionalmanner, such as by silk-screening or other types of printing. The filmcan be decorated on both first and second surfaces, but is commonlydecorated on only the surface that is not exposed to wear and theenvironment (the second surface in many cases). The fact that the text,pattern, or graphics is printed on the opposite (second) side of thefilm also protects the text, pattern, or graphics from such potentiallydamaging exposure. Because the film is typically light-transmissive,second-surface decorations will be visible through the film after theproduct is completed. The first surface is exposed to wear and theenvironment, and so may need protection from scratches, abrasion,fluids, and the like. Therefore, the first surface is coated with theprotective coating. The hardcoat is left uncured so that it can beformed with the film later in the process.

[0005] With continued reference to FIG. 1, after the decorations andprotective coating have been applied to the surfaces of the film as justdescribed, the film is formed into a desired shape in one of severalconventional manners. For example, the film can be vacuum thermoformed,pressure formed, hydroformed, matched metal formed, etc. Considerationsin the type of forming operation selected include the amount of filmshaping to be performed (referred to as the amount of “draw” needed forthe desired final shape, such as a deep draw or shallow draw), and theextent to which the forming operation will damage or affect theprotective coating. It is this latter consideration that presentssignificant problems in conventional IMD processes. Specifically,conventional protective coatings typically need to be cured to achievetheir strong and wear-resistant properties. However, once cured, thesesame properties largely limit the ability of these protective coatingsto be stretched, bent, compressed, or otherwise formed without damage.While this is not normally a problem with protective coatings upon afinal product, it is a significant problem in the film forming operationdescribed above. Therefore, protective coatings are typically leftuncured in conventional IMD processes until after the film formingprocess.

[0006] Although the uncured protective coating can be easily shapedwithout sustaining damage, it is relatively delicate and susceptible toscratching, marring, impressions, and the like. By way of example only,such damage can occur as the film is being taken out of the printing andcoating machinery, when the film is stacked upon other films fortransport or otherwise, during movement and handling of the film fromthe printing and coating machinery to the molding machinery, when thefilm is inserted into the molding machinery, during the moldingoperation, when the film is removed from the molding machinery, andduring movement and handling of the film from the molding machinery to alocation where the protective coating is cured.

[0007] In order to protect the uncured protective coatings from damage,special procedures are commonly used, such as restrictions on the amountof film stacking, protection of the film from exposure to light and heat(many protective coatings are cured by exposure to ultraviolet lightand/or heat), procedures for particular care in handling the films, andthe like. In addition, the ability of many forming operations andmachinery to damage the uncured protective coating limits the types ofoperations and machinery that can be used. The special handlingprocedures and the inability to employ many types of machinery andprocessing operations just described represent significant limitationsof conventional protective coatings and affects the entire IMD process.These limitations inevitably increase the inefficiency and cost ofproduction of the IMD process and therefore of the end product.

[0008] Even with special handling procedures and the use of specificmachinery to avoid protective coating damage, the delicate uncuredprotective coatings inevitably increase the scrap rate of films and theproducts made with such films. In some cases, even a small number ofscrapped films can significantly impact production costs.

[0009] Yet another limitation of conventional protective coatings isrelated to their resulting appearance and performance, and isindependent of whether the surface provided with the protective coatingis later molded or otherwise shaped. In this regard, it should be notedthat conventional protective coatings are commonly applied to a numberof different surfaces that are not later molded or otherwise shaped.Although a number of conventional protective coatings are strong andwear resistant, the ability of a manufacturer to control the appearanceof the final coated product can often be quite limited. Protectivecoatings that can be opaque or transparent and that can have a range ofglossy, matte, and textured finishes are highly desirable, but arenormally not available in one conventional protective coating.

[0010] In light of the problems and limitations of the prior artdescribed above, a need exists for a protective coating that can beemployed in IMD processes, is strong and wear-resistant, can be curedprior to forming operations of the underlying substrate, is sufficientlyflexible and formable after curing to withstand such forming operationswithout damage, enables the use of a wider variety of molding machineryto form the underlying substrate, reduces the chances of coating damageduring substrate printing, handling, transport, and molding processes,reduces scrap rates and production costs, can be transparent or can bepartially or fully opaque, and can have a range of finishes (from glossyto matte and a range of textures). Each preferred embodiment of thepresent invention achieves one or more of these results.

SUMMARY OF THE INVENTION

[0011] In some preferred embodiments of the present invention, aprotective coating is preferably formed as a plurality of dots on asubstrate or object which is desired to be protected. As described ingreater detail below, the dots can be any shape, can have the same ordifferent shapes, and can be in any density and in any pattern (or nopattern) on the substrate or object. Preferably, the dots are isolatedor substantially isolated from one another by uncoated surfaces of thesubstrate or object, thereby not only providing the substrate or objectand the coating with significantly increased cured flexibility andformability, but also with a wide range of possible surface finishes andtextures.

[0012] Due to the increased flexibility and formability of someembodiments of the protective coating even after being cured, the coatedsubstrate or object can be partially or even fully cured prior toforming operations such as injection molding or film shaping. Thesubstrate or object is therefore less susceptible to damage fromhandling and from machine operations. This reduces the scrap rate of thesubstrates or objects being produced and therefore lowers productioncosts and the cost of the end product. In addition, because theprotective coating can be partially or fully cured before formingoperations, more types of machines and methods (that could otherwisedamage uncured protective coatings) can be employed for forming,shaping, and other manufacturing operations upon the substrate or objectbeing produced.

[0013] Although the dots of the protective coating can be applied to asurface in any desired arrangement or pattern, the dots are morepreferably applied in an arrangement that is known to present a uniformand pleasing appearance to the protective coating. Most preferably, thisarrangement is stochastically generated and is repeatedly reproducedover the surface to be protected. The dots can be any average size, butpreferably are an average of between 50 and 150 microns, more preferablyare an average of between 80 and 100 microns, and most preferably areapproximately 90 microns. The dots can also cover any amount of thesurface area to be protected, but preferably cover between 20% and 70%of the surface area, more preferably cover between 20% and 40% of thesurface area, and most preferably cover approximately 25% of the surfacearea.

[0014] The protective coating material and the resulting protectivecoating can be any color desired, but is preferably transparent orsubstantially transparent. In this manner, the surface beneath theprotective coating can be printed or otherwise provided with text orgraphics and can have any desired color visible through the protectivecoating. The protective coating is preferably a second surfaceprotective coating, and can be applied over text or graphics on thefirst or second surfaces of a film or other object.

[0015] Preferably, the protective coating material is an ink that isscreen printed upon the surface to be protected. However, otherconventional printing and application methods can instead be employed ifdesired. After being applied to the surface, the protective coatingmaterial is preferably cured by exposure to ultraviolet light, althoughother curing methods are possible (including exposure to air and toheat) depending upon the type of protective coating material used. Oncecured, the dots defining the protective coating enable the surface andthe protective coating to be flexed and formed without damage, or atleast without sufficient protective coating damage to compromise productquality. At the same time, the dots are sufficiently close together toprotect the underlying surface from fluids, abrasion, stains, and otherdamage.

[0016] In some highly preferred embodiments, the protective coating canbe pre-cured to control the end appearance of the protective coating. Inthe case of ultraviolet-cured protective coating materials, theprotective coating can be initially exposed to relatively low-wattageultraviolet light. This exposure preferably generates stipple upon thesurfaces of the dots defining the protective coating, and can be furtherenabled by the use of gas flow (e.g., a nitrogen knife) over the dotsduring exposure to the low-wattage ultraviolet light. Thereafter, theprotective coating material can be exposed to higher wattage ultravioletlight to complete the curing process. The amount of stipple can becontrolled by (among other factors) controlling the intensity of thelow-wattage ultraviolet light, the length of protective coating exposurethereto, and the amount of gas flow over the protective coating.

[0017] A surface coated with the protective coating of the presentinvention can be provided with a much wider variety of final appearancesand textures than is possible with conventional protective coatings andcoating methods. In particular, the number and pattern (if any) of dots,the average dot size, the amount of surface area covered by the dots,and the type of protective coating material used can all be altered togenerate a range of protective coating appearances and textures. An evenlarger range of appearances and textures are possible by generating andcontrolling the degree of stipple upon the surfaces of dots as describedabove.

[0018] These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims, andappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a flowchart of a typical IMD process according to theprior art;

[0020]FIG. 2 is a flowchart of an IMD process according to a preferredembodiment of the present invention;

[0021]FIG. 3 is a cross-sectional perspective view of a printedsubstrate having a protective coating according to a preferredembodiment of the present invention; and

[0022]FIG. 4 is a plan detail view of the coating shown in FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0023] A large number of significant advantages are provided by theprotective coating of the present invention when employed in an IMDprocess in which a film is formed into a desired shape after beingprinted. The film is preferably plastic, and more preferably is aconventional polycarbonate plastic or polyester-polycarbonate plasticalloy. However, one having ordinary skill in the art will recognize thatthe present invention can be employed in conjunction with a number ofother conventional films, each one of which falls within the spirit andscope of the present invention. By way of example only, such other filmsinclude without limitation polyester, acrylic, and styrene films. Thefilms can be any thickness desired, subject to the manner in whichmolding is performed upon each type of film. In particular, the moldingequipment and process used to mold a film normally performsatisfactorily up to a maximum thickness for that film. The maximumthickness of each film is dependent upon factors such as film stiffness,response to temperature, and the like.

[0024] Although well-suited for protecting films such as those describedabove, some embodiments of the present invention are independent ofsubstrate thickness. The protective coating of the present invention canbe applied to many different types of substrates, whether in film formor not, whether later molded or otherwise shaped, and whether placedthrough later manufacturing processes or not (e.g., used as an insertfor later injection molding, adhered or otherwise attached to anotherpart, and the like). In short, the present invention can be used inconjunction with parts having any shape or size, and is described hereinwith reference to plastic films only by way of preferred example.Accordingly, the term “substrate” as used herein and in the appendedclaims includes any coatable part having any shape and size.

[0025] An IMD molding process according to a preferred embodiment of thepresent invention is illustrated in flowchart form in FIG. 2. First, thesecond surface of the film is preferably decorated with graphics, apattern, and/or text as described above. In other embodiments, the firstsurface can also or instead be decorated if desired. The surface(s) arepreferably screen printed in a conventional manner, although any othermanner of decoration can be employed. If necessary, the decorationprocess can involve multiple printing steps, such as printing one ormore colors or portions of the final decoration in steps.

[0026] Next, the protective coating of the present invention is appliedto the film. The protective coating can be applied to the second surfaceover the decorations thereon, but more preferably is applied to thefirst surface. In other embodiments, the protective coating is appliedto both first and second surfaces of the film.

[0027] The protective coating in the most preferred embodiment isapplied in fluid form to the first surface, and can be applied theretoin any conventional manner. The protective coating can be printed uponthe first surface, and in some highly preferred embodiments is screenprinted thereon. In other highly preferred embodiments, the protectivecoating is pad printed upon the first surface. Screen and pad printingcan be performed in a number of manners well known to those skilled inthe art and are not therefore described further herein. Still otherconventional manners of printing are possible and can be employed toapply the protective coating to the first surface, each one of whichfalls within the spirit and scope of the present invention.

[0028] Next, the protective coating is preferably cured on the film.Depending upon the type of protective coating material used, theprotective coating can be cured in a number of different manners. Mostpreferably, the protective coating is cured by exposure of the coatingmaterial to ultraviolet light, although other highly preferredembodiments employ protective coatings that are cured by exposure toheat. The protective coating material can be exposed to ultravioletlight emitters (e.g., in the form of light bulbs, fiber optic lenses,and the like) in any conventional manner. As will be described in moredetail below, the protective coating is printed in a manner such thatthe cured protective coating is preferably capable of flexing andforming with the film without damage to the protective coating. This isvery different from conventional cured protective coatings that tend tocrack, peel, detach (from the substrate) and chip when the substrate isflexed or otherwise formed due to the loss of coating materialflexibility once cured. This is less of a concern in those applicationswhere the coated surface is not later exposed to flexure or forming.However, the improved control over coating and finished productappearance provided by the present invention also provides importantadvantages over conventional protective coatings as described in moredetail below.

[0029] If desired, the film can be further decorated after theprotective coating process, such as by the application of graphics, apattern, and/or text upon the protective coating material or upon anuncoated surface. After the protective coating curing process, theprinted and coated film is preferably placed in a molding machine. Themolding machine can be of any conventional type capable of forming thefilm into a desired shape. By way of example only, the molding machinecan be a thermoforming, pressure-forming, hydroforming, or matched metalmachine (with rubber or other elastomeric forming inserts if desired).In some applications, it is even possible to form the film using aninjection molding machine in which the film is placed in the injectionmolding machine and is formed in an injection molding operation with hotresin in the molding cavity. One having ordinary skill in the art willappreciate that still other types of molding machines can be employed toform the film. Because the protective coating upon the film has alreadybeen cured, the protective coating can withstand greater pressuresduring the molding process and in some preferred embodiments can beexposed to significant contact without being blemished, scratched, orotherwise damaged. As described in greater detail below, the curedprotective coating is also capable of deeper draw molding operationswithout being damaged.

[0030] With continued reference to FIG. 2, the molded film is thenremoved from the molding machine and is cut and trimmed as desired usingany conventional cutting and trimming techniques and equipment. Amongother purposes, this cutting and trimming operation can be performed toproperly fit the molded film into an injection molding machine.

[0031] Finally, in those cases where later injection molding is desired(if not performed with the film forming operation as described above),the molded film is preferably inserted within an injection moldingmachine for injection molding upon at least the second surface of thefilm. Preferably, the resulting injection molded part has an exteriorsurface with a cured protective coating and has text, a pattern, and/orgraphics located behind the coated film and therefore not exposed tocontact, wear, and the environment.

[0032] A number of different protective coating materials can be usedwith the present invention. Some conventional protective coatingmaterials that can be used are cured by being subjected to heat, air,chemicals (e.g., in gaseous form acting as a catalyst), and light. Morepreferably however, the protective coating material is an ink that iscured by exposure to ultraviolet light. Examples of such inks includenitrogen cured and non-nitrogen cured inks. Although either type ofultraviolet cured ink (and still other inks) can be employed in thepresent invention, a nitrogen cured ultraviolet ink is most preferred.Protective coating materials and inks and their properties are wellknown to those skilled in the art and are not therefore describedfurther herein.

[0033] The protective coating of the present invention is capable ofbeing formed after being cured, thereby providing significant advantagesover conventional protective coatings that must remain uncured untilfilm forming operations are complete. This coating flexibility is due atleast in part to the form of the protective coating upon the film (orother substrate desired to be provided with a protective coating).Specifically, the protective coating is preferably defined by a numberof substantially isolated dots as opposed to an unbroken layer ofmaterial.

[0034] With reference to FIGS. 3 and 4, each dot takes the form of anisland surrounded by substantially uncoated portions of the substrate.Each dot can take any shape desired, including without limitationsquare, rectangular, triangular, and other polygonal shapes, round,oval, elliptical, crescent, and other curved shapes, star, football,egg, polymorphous, and other unusual shapes, and the like. In somehighly preferred embodiments such as that shown in FIGS. 3 and 4, thedots have irregular shapes.

[0035] The dots defining the protective coating can all be identical orsubstantially identical, but more preferably are different to somedegree. This can be accomplished with the selection of two or moredifferent types of dot shapes in any desired ratio. In some embodiments,each dot has a random shape that is unique or is preferably only similarto the shape of other dots by coincidence. Most preferably, a number ofdifferent dot shapes (irregular as shown in FIG. 4 and/or regular) areemployed and are scattered with respect to one another and arepreferably sized and arranged to be substantially invisible (from ashort distance) to the naked eye.

[0036] In some highly preferred embodiments, the dots all covercomparable amounts of surface areas upon the substrate, even though thedot shapes may vary. Other embodiments can employ dots coveringdifferent amounts of substrate surface area, in which any frequency ofeach dot size can be selected as desired. The protective coating of thepresent invention can be applied over any portion or portions or all ofa substrate or object, such as over an entire side of a substrate, inonly those areas that are visible to a user of the end product, in areasthat are intended to have a desired appearance in contrast to adjacentor other areas of the substrate or object, in a pattern of areas overthe substrate or object, in areas that are subject to greater contactand wear, and the like.

[0037] The dots of the protective coating can be any size desired.However, superior results have been achieved with dot sizes between 50and 150 microns (the average diameter or length of the dots). Morepreferably, the average dot size is between 80 and 100 microns. Mostpreferably, the average dot size is approximately 90 microns. Althoughother printing resolutions are possible and can be used in the presentinvention, a 4,000 pixel per square inch (ppi) resolution is preferred.

[0038] As described above, the dots are preferably separated orsubstantially separated from one another by uncoated substrate areas. Asa result, the protective coating can flex between the dots withoutimparting damaging stresses upon the dots themselves. The averagedistance between the dots is preferably a function of the dot sizedescribed above and the amount of surface area covered by the dots.Although virtually any amount of surface area greater than 0% and lessthan 100% can be covered by the dots, preferred results have beenachieved when the dots cover between 20% and 70% of the surface area.More preferably, the dots cover between 20% and 40% of the surface area.Most preferably, the dots cover approximately 25% of the surface area.

[0039] In addition to the protective coating flexibility and formabilityof the present invention, the hardcoat material dots protect againstscratching, scuffing, and other abrasion, marring, and the like. Also,because the dots are located sufficiently close together, they limit theability of fluid, objects, and other debris to get between the dots andto reach the underlying substrate. The substrate is therefore protectedagainst blemishing and staining (e.g., from oils, foods and drinks,cleaning solutions, and the like).

[0040] It will be clear to one having ordinary skill in the art that thedots do not necessarily have to be completely isolated from contact withone another to arrive at the present invention. The dots should beseparated enough to permit flexibility of the protective coating withthe underlying substrate by relative motion of the dots rather than byimparting excessive stresses from one dot to another. Accordingly, insome embodiments the dots can contact one another and can even havebridges of hardcoat material connecting one another while still havingflexibility provided by spaces between the dots. In these and otherembodiments, a relatively thin layer of hardcoat material can cover thespaces between the dots while permitting relative motion of the muchthicker dots without impermissible damage thereto. In this regard, itshould be noted that high and even damaging stresses can be acceptablein a finished coated product. Specifically, these stresses can create anacceptable amount of damage to the dots and protective coating. Suchdamage includes damage that is invisible to the naked eye and that willnot magnify to macroscopic protective coating damage over time andenvironmental exposure, and damage that will not lead to peeling orvisible cracking (eventually compromising the integrity of theprotective coating).

[0041] Substantially isolated dots as just described still perform thesubstrate-protective functions described above. More preferably however,the dots of the protective coating are each entirely separated from oneanother by substrate having no hardcoat material thereon.

[0042] Another feature of the protective coating according to thepresent invention (in addition to the substrate protecting andflexibility features) relates to the appearance of the coated substrate.The relative placement of the dots upon the substrate can significantlyimpact the protective coating's appearance. Therefore, in some preferredembodiments, the dots defining the protective coating are placed inlocations and in an arrangement upon the substrate to result in adesired finish and appearance of the cured protective coating. The dotscan be located and arranged in any manner, including without limitationin an array or grid, completely randomly, in any predetermined pattern,and the like. In addition, the dots can be arranged in any orientation.While this applies to dots having specific shapes (e.g., rectangular orotherwise elongated dots all oriented in a particular direction and/ororiented in a desired manner with respect to one another, the sides ofsquare dots being parallel to one another, etc.), this applies toirregularly-shaped dots as well (e.g., dots having a length greater thana width being oriented in a particular direction and/or oriented in adesired manner with respect to one another, etc.).

[0043] A smooth and uniform appearance is desirable in many protectivecoatings. Therefore, because a completely random deposit of dots oftenpresents less than a smooth and uniform appearance as is well-known tothose skilled in printing and related arts, a predetermined pattern orarrangement of dots is used in some highly preferred embodiments of thepresent invention. With reference for example to FIG. 4, an arrangementof dots is preferably employed that is known to present a uniformappearance to the protective coating. This arrangement is comprised of apattern of dots oriented and positioned in a desired manner, and can bereproduced again and again over the surface of the substrate. Althoughany material deposition or printing process can be used to coat thesubstrate with the pattern, the dots are most preferably printed by aconventional screen printing process. The pattern can be a fraction of amillimeter in size or can be larger if desired. The pattern can bedesigned, but is preferably randomly generated in any conventionalmanner. Most preferably, the pattern is generated by stochastic printingmethods, and is repeatedly reproduced as just described over the surfaceof the substrate.

[0044] In some preferred embodiments of the present invention, the dotsare preferably the same or substantially the same height as best shownin FIG. 3 and can have any side profile shape desired. In otherembodiments, the dots have different heights.

[0045] As mentioned earlier, the protective coating material ispreferably a nitrogen ultraviolet cured or non-nitrogen ultravioletcured ink, and is more preferably a nitrogen ultraviolet cured ink. Anon-nitrogen ultraviolet cured ink is preferably cured by exposure toconventional ultraviolet bulbs or other ultraviolet light emitters. Forexample, the coated film or object can be exposed to relativelyhigh-wattage multiple banks of mercury vapor and/or gallium ultravioletbulbs. These banks of bulbs can have varying intensities for differentcuring results. Any number of banks can be used, and each bank can haveany number of ultraviolet bulbs. By way of example only, the coated filmor object can be exposed to a single ultraviolet bulb until cured, orcan be exposed to three banks of four high wattage mercury vapor bulbsfollowed by three banks of four higher wattage gallium bulbs. Ifmultiple banks of bulbs are used, the coating can be exposed todifferent types and wattages of ultraviolet bulbs in any desired order.

[0046] In some preferred embodiments of the present invention, thesubstrate or object coated with the uncured or partially curedprotective coating is placed upon a conventional conveyor. The conveyorcan retain the substrate or object upon the conveyor in any conventionalmanner, such as with an electrostatic charge or by a vacuum force as iswell known to those skilled in the art. Other conveyors do not retainthe substrate or object as it is moved. The conveyor preferably movespast the banks of ultraviolet bulbs at a desired speed or speeds toexpose the coating material to ultraviolet light for desired lengths oftime. It will be appreciated by one having ordinary skill in the artthat other manners exist for exposing the coating material to one ormore banks of ultraviolet bulbs for predetermined periods of time, eachone of which falls within the spirit and scope of the present invention.For example, banks of bulbs can be conveyed or otherwise moved intoexposing position adjacent to the coated substrate or object. As anotherexample, the substrate or object can be moved to a bank of the same orvarious types and wattages of bulbs, any number of which can be turnedon and off for predetermined periods of time during the curing process.

[0047] Some degree of control over the coated surface or object'sappearance is possible by changing the type of protective coatingmaterial being used. For this purpose, many conventional coatingmaterials are available for providing different surface appearances andtextures. For example, inks having fine, medium, and coarse finishes areavailable and can be used to produce matte, satin, glossy, and othersurface appearances, and to a lesser extent can be used to produce somesurface textures. Therefore, the protective coating of the presentinvention can be made with dots of any desired protective coatingmaterial type to produce a range of dot surface appearances andtextures, thereby providing a range of surface appearances and textures.

[0048] More preferably however, the surfaces of the dots are shaped in apre-curing or “soft-curing” process in which a surface of the protectivecoating is first cured to produce stipple upon the protective coatingsurface. Although an amount of control of surface appearance and eventexture is possible by using different coating materials in the presentinvention as described above, the inventor has found that much morecontrol and better results are possible by employing a soft-curingprocess. In this process, as an outer layer of the protective coatingmaterial cures, it moves over the underlying uncured coating material.The outer layer therefore forms in an uneven manner (generates“stipple”) over the remainder of the underlying uncured protectivecoating material. This is performed using lighter initial curingintensity (e.g., less powerful light in the case of ultraviolet curedinks). After the surface of the protective coating has been cured, theremainder of the protective coating is preferably cured with higherintensity. By controlling the amount of initial curing intensity andexposure time, the coating stipple can be increased or decreased,thereby generating a relatively large range of coating surfaceappearances and textures.

[0049] For example, some highly preferred embodiments employ a nitrogenultraviolet curing process to generate stipple on the surface of theprotective coating described above. Using a nitrogen ultraviolet curedink, the surface or object coated with the dots of uncured protectivecoating is exposed to relatively low-wattage ultraviolet bulbs (forexample, germicidal ultraviolet bulbs). To enhance this part of thecuring process, a flow of gas can be directed over the surface beingexposed to the low-wattage ultraviolet bulbs. A flow of nitrogen gas(sometimes called a “nitrogen knife”) has been found to be veryeffective for this purpose, although other types of gas can be used asdesired. The gas flow is preferably used to help cure the surface of theprotective coating material by removing oxygen therefrom. As mentionedabove, the amount of exposure to the low-wattage bulbs and the intensityof the low-wattage bulbs can be selected from respective exposure andwattage ranges to generate a desired stipple on the protective coating.In this regard, the amount of gas flow over the coating material canalso be increased or decreased to change the degree of curing, thestipple, and therefore the resulting coating appearance and texture.

[0050] After the soft-curing process has been completed to generate adesired coating surface stipple as just described, the coated surface orobject is preferably exposed to higher intensity ultraviolet light tocomplete the curing process as described in greater detail above.Preferably, the low-wattage curing and the following high-wattage curingis performed by conveying the coated surface or object past banks ofultraviolet bulbs as also described above, in which case the flow of gas(e.g., the nitrogen knife) is preferably located adjacent to the bank orbanks of low-wattage bulbs.

[0051] The appearance of the protective coat can be controlled by thesize and shape of the dots defining the protective coat, the spacingbetween the dots, the protective coating material used, the amount (ifany) of stipple on the surface of the dots, and the finish of theunderlying substrate. The size, shape, and stipple of the dots and thespacing between the dots can affect the manner in which light reflectsfrom the protective coating, thereby imparting a more glossy or matteappearance or a texture to the protective coating. Also, the protectivecoating material can be transparent or can be opaque, and can be coloredusing any conventional technique or coating material additive.

[0052] In many applications, it is possible (and highly desirable) tofirst print or otherwise coat the film or other object with a finish.This finish can give the coated object an appearance ranging from glossyto matte and can even provide the coated object with a texture. Althoughthe finish can be applied upon the second film surface, it is morepreferably applied upon the first surface of the film or other object.The finish is preferably screen printed, but can be deposited in anyother conventional manner desired. Such finish application andtechniques for applying finishes are well known to those skilled in theart and are not therefore described further herein. After the finish isapplied, the above-described protective coating can be appliedthereover. The finish is preferably visible at least between the dotsdefining the protective coating, and more preferably is visible througha transparent protective coating as well as between the dots. In eithercase, the term “substrate” includes the film or object being coated aswell as the finish applied thereto (and any other layers of materialapplied to the film or object before the protective coat).

[0053] The embodiments described above and illustrated in the figuresare presented by way of example only and are not intended as alimitation upon the concepts and principles of the present invention. Assuch, it will be appreciated by one having ordinary skill in the artthat various changes in the elements and their configuration andarrangement are possible without departing from the spirit and scope ofthe present invention as set forth in the appended claims. For example,the present invention is described above in the context of an in-molddecoration (IMD) process. It should be noted, however, that theprotective coating of the present invention can be employed to coat anyobject regardless of whether the object is later molded or otherwiseformed and regardless of the manner in which such molding or forming isperformed (subject only to the ability of the protective coating towithstand the molding or forming process selected without damage). Inthis regard, the substrate coated with the protective coating need notbe a plastic film, and can be any object capable of being coated.Therefore, some parts that are provided with a protective coatingaccording to the present invention may not have a “second surface” asdescribed above with reference to the illustrated IMD process. In suchcases, the protective coating is only provided on the first surface overany earlier-applied text or graphics.

[0054] In the preferred embodiments of the present invention describedabove and illustrated in the figures, the substrate (and protectivecoating) is shaped after the protective coating is fully cured, whetherin a single curing process or with an additional pre-curing process asdescribed in greater detail above. In other embodiments, the protectivecoating need not necessarily be cured or fully cured prior to molding orforming operations. The protective coating can be cured at any stage inmaking the product, although significant benefits exist to at leastpartially curing the protective coating prior to molding or formingoperations. In some embodiments, the protective coating material can bepartially cured to resist damage from handling and shaping (whileremaining highly flexibility and formability for shaping), and can thenbe fully cured to achieve the cured protective coating propertiesdescribed above. For example, the coated substrate or object can beformed after the pre-curing process used for stipple generationdescribed above. As another example, the coated substrate or object canbe fully or partially formed after being partially cured withhigh-wattage ultraviolet bulbs as also described above.

The invention claimed is:
 1. An article, comprising: a substantiallyrigid substrate made of a material that softens to a state permittingpermanent deformation when the substrate is heated; a first surfaceprotective coating, comprising a layer of cured material printed uponthe substrate, the layer of cured material defined by a plurality ofdots stochastically printed upon the substrate and substantiallyseparated from one another by substantially exposed areas of thesubstrate to permit deformation of the substrate when heated withoutdamage to the protective coating.
 2. The article as claimed in claim 1,wherein the substrate is a light-transmissive substrate.
 3. The articleas claimed in claim 1, wherein the substrate has at least one of textand graphics printed upon a second surface of the substrate.
 4. Thearticle as claimed in claim 1, wherein the layer of cured material issubstantially transparent.
 5. The article as claimed in claim 1, whereinthe layer of cured material is a screen-printed layer of cured material.6. The article as claimed in claim 1, wherein the plurality of dotsincludes a stochastically-generated pattern of dots repeated upon thesubstrate.
 7. The article as claimed in claim 1, wherein the substrateand protective coating are formable without damage to the layer of curedmaterial on the substrate.
 8. The article as claimed in claim 1, whereinthe substrate is comprised of a polyester-polycarbonate alloy.
 9. Thearticle as claimed in claim 1, wherein the plurality of dots havestipple thereon.
 10. The article as claimed in claim 1, wherein the dotshave an average size of between 50 and 150 microns.
 11. The article asclaimed in claim 1, wherein the dots have an average size of between 80and 100 microns.
 12. The article as claimed in claim 1, wherein the dotshave an average size of about 90 microns.
 13. The article as claimed inclaim 1, wherein the dots cover between 20% and 70% of the printedsubstrate.
 14. The article as claimed in claim 1, wherein the dots coverbetween 20% and 40% of the printed substrate.
 15. The article as claimedin claim 1, wherein the dots cover about 25% of the printed substrate.